This invention relates in general to fiber-optic receiver/transmitter arrangements and more specifically to a novel laser driver circuit for a fiber-optic transmitter.
Fiber-optic receivers and transmitters or fiber-optic interface units are used in modern telecommunications and data transmission systems between an optical fiber transmission line and electronic digital equipment. The fiber-optic transmitter receivers electrical signals from the electronic equipment representing the data to be transmitted. The transmitter then converts the data to light pulses which are coupled to an optical fiber transmission line. The fiber-optic receiver receives light pulses representing the transmitted data from an optical fiber transmission line and converts the light pulses to electrical signals which are sent to and processed by the electronic digital equipment. These systems work in very high transmission rates from 145 Mbs to 2400 Mbs (Megabits per second).
Transmission of data or other signals along optical fiber transmission lines have advantage in the fact that light rays are almost immune to electromagnetic interference such as sparks, lightening, crosstalk and other interference which may be induced into the transmission line.
Laser driver circuits, found in the fiber-optic transmitter, receive data to be transmitted at electrical signals usually in the form of pulse modulation from the digital equipment. The laser driver uses the received modulation to trigger a solid state laser emitter thereby, converting the electrical signals into light pulses.
These circuits require extremely stable operating characteristics since the speed of modulation that the circuit operates in is in the range of over 100Mbs (megabits per second). Further, since the modulation speed is close to the microwave region the circuit must operate relatively free from spurious oscillations which would cause it to malfunction and erroneously modulate the laser.
It therefore becomes an object of the present invention to disclose a novel laser driver circuit exhibiting all of advantageous discussed above.